Neuroimaging and behavioral studies have shown that brands convey meaning to consumers. How the brain immediately reacts to brand logos followed by either congruent or incongruent pictorial brand cues can deepen the understanding on the semantic processing of brands. Previous studies on linguistics have found different brain responses to congruent vs incongruent stimuli, which was attributed to the process of error monitoring. Our study investigated whether brands lead to the same brain reactions. Thirty-two participants (13 female, mean age 26.84 ± 4.33) performed the task, wearing 32-channel EEG cap. Forty congruent and forty incongruent 2D brand related image sequences were shown through a virtual reality headset. Each sequence comprised three images implying a brand, a question, and the brand logo. The congruence manipulation happened in the brand logo. Then, preprocessed signals of the last image were first averaged among each condition to obtain ERP activity, and then the time-frequency activity of each trial was calculated using welch method. Time-frequency analysis was implemented on theta frequency band (4-7 Hz), and time interval of 700 to 1200 ms after stimulus start. The analyses were implemented on central region electrodes based on literature, and two dimensional permutation test was conducted to test the statistical significance. The ERP analysis showed significant difference between the two conditions (congruent > incongruent) in the N400 component (p= 0.04, effect size= 0.54), in which the incongruent condition had a larger negative peak. The results showed that theta activity of congruent (versus incongruent) condition is significantly lower (p= 0.01, effect size= -0.69). This study showed that brain response to congruent versus incongruent brand logo differed in both time (ERP) and time-frequency domain. Studies in linguistic field have suggested that difference in central and mid-frontal region due to stimuli congruence is related to error monitoring process. This study replicated their findings. Thus, we argue there is a higher processing difficulty in mismatched (versus matched) brand logos, leading to a larger error monitoring. Therefore, error monitoring process could be extended to other forms than linguistic, such as images and brands. Moreover, theta band difference occurred in 700-1200 ms while ERP difference occurred in N400 component. This finding suggests that these two methods capture different aspects of brain activity.